Yep, one of the other Helens posts, I commented on that.
During the eruption, the top 1300 feet and most of the north face blew off with an explosion equivalent to a 20 megaton nuclear bomb.
Did you know that animals survived that? Burrowing ones. They had a stash of food. A while afterwards they came up and churned up the earth, and allowed flowers to start to grow. Well, flowers were already growing. Little ones :)
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Not to mention that this eruption did about 1.5 billion in damages... In 1980's dollars. Adjusted for inflation, it's something like 2.5-2.8.
During the eruption, the top 1300 feet and most of the north face blew off with an explosion equivalent to a 20 megaton nuclear bomb.